Infra-red detector



FIG. 1 is a front three-quarter perspective view of an infra-red detector embodying our new design;

FIG. 2 is a top plan view thereof, the bottom being a mirror image;

FIG. 3 is a front elevational view thereof; and

FIG. 4 is a side elevational view thereof, the right side being a mirror image.

The rear is flat and unornamented. 

The ornamental design for an infra-red detector, as shown and described. 